An airplane has a fuel system used for supplying a needed amount of fuel to a combustion engine. Such a fuel system is provided with a fuel pump which increases the pressure of fuel discharged from a fuel tank. A constant-volume pump or a centrifugal pump is used for the fuel pump, and the constant-volume pump includes a gear pump or the like.
Although Patent Document 1 or 2 proposes a configuration in which an electric motor is used for the driving source of the fuel pump, in this configuration, the size of the fuel system may be increased and the fuel system may be complicated. In addition, since electric power used for driving the electric motor is generated using power of the engine, a loss due to electric power conversion may occur, and thus the energy efficiency may deteriorate. Accordingly, it is preferable that the fuel pump be connected to the engine and be driven using rotational power output from the engine.